Tag Archives: micelles

A Northwestern University research team is the first to capture on video organic nanoparticles colliding and fusing together. This unprecedented view of “chemistry in motion” will aid Northwestern nanoscientists developing new drug delivery methods as well as demonstrate to researchers around the globe how an emerging imaging technique opens a new window on a very tiny world.

This is a rare example of particles in motion. The dynamics are reminiscent of two bubbles coming together and merging into one: first they join and have a membrane between them, but then they fuse and become one larger bubble.

“I had an image in my mind, but the first time I saw these fusing nanoparticles in black and white was amazing,” said professor Nathan C. Gianneschi, who led the interdisciplinary study and works at the intersection of nanotechnology and biomedicine.

“To me, it’s literally a window opening up to this world you have always known was there, but now you’ve finally got an image of it. I liken it to the first time I saw Jupiter’s moons through a telescope. Nothing compares to actually seeing,” he said.

Gianneschi is the Jacob and Rosaline Cohn Professor in the department of chemistry in the Weinberg College of Arts and Sciences and in the departments of materials science and engineering and of biomedical engineering in the McCormick School of Engineering.

The study, which includes videos of different nanoparticle fusion events, was published today (Nov. 1 [2017]7) by the Journal of the American Chemical Society.

The research team used liquid-cell transmission electron microscopy to directly image how polymer-based nanoparticles, or micelles, that Gianneschi’s lab is developing for treating cancer and heart attacks change over time. The powerful new technique enabled the scientists to directly observe the particles’ transformation and characterize their dynamics.

“We can see on the molecular level how the polymeric matter rearranges when the particles fuse into one object,” said Lucas R. Parent, first author of the paper and a National Institutes of Health Postdoctoral Fellow in Gianneschi’s research group. “This is the first study of many to come in which researchers will use this method to look at all kinds of dynamic phenomena in organic materials systems on the nanoscale.”

In the Northwestern study, organic particles in water bounce off each other, and some collide and merge, undergoing a physical transformation. The researchers capture the action by shining an electron beam through the sample. The tiny particles — the largest are only approximately 200 nanometers in diameter — cast shadows that are captured directly by a camera below.

“We’ve observed classical fusion behavior on the nanoscale,” said Gianneschi, a member of Northwestern’s International Institute for Nanotechnology. “Capturing the fundamental growth and evolution processes of these particles in motion will help us immensely in our work with synthetic materials and their interactions with biological systems.”

The National Institutes of Health, the National Science Foundation, the Air Force Office of Scientific Research and the Army Research Office supported the research.

An Aug. 29, 2016 news item on Nanowerk announces research into determining the presence of engineered (synthetic) nanoparticles in bodies of water,

For a number of years now, an increasing number of synthetic nanoparticles have been manufactured and incorporated into various products, such as cosmetics. For the first time, a research project at the Technical University of Munich and the Bavarian Ministry of the Environment provides reliable findings on their presence in water bodies.

Nanoparticles can improve the properties of materials and products. That is the reason why an increasing number of nanoparticles have been manufactured over the past several years. The worldwide consumption of silver nanoparticles is currently estimated at over 300 metric tons. These nanoparticles have the positive effect of killing bacteria and viruses. Products that are coated with these particles include refrigerators and surgical instruments. Silver nanoparticles can even be found in sportswear. This is because the silver particles can prevent the smell of sweat by killing the bacteria that cause it.

Previously, it was unknown whether and in what concentration these nanoparticles enter the environment and e.g. enter bodies of water. If they do, this poses a problem. That is because the silver nanoparticles are toxic to numerous aquatic organisms, and can upset sensitive ecological balances.

Analytical challenge

In the past, however, nanoparticles have not been easy to detect. That is because they measure only 1 to 100 nanometers across [nanoparticles may be larger than 100nm or smaller than 1nm but the official definitions usually specify up to 100nm although some definitions go up to 1000nm] – a nanometer is a millionth of a millimeter. “In order to know if a toxicological hazard exists, we need to know how many of these particles enter the environment, and in particular bodies of water”, explains Michael Schuster, Professor for Analytical Chemistry at the TU Munich.

This was an analytical challenge for the researchers charged with solving the problem on behalf of the Bavarian Ministry of the Environment. In order to overcome this issue, they used a well-known principle that utilizes the effect of surfactants to separate and concentrate the particles. “Surfactants are also found in washing and cleaning detergents”, explains Schuster. “Basically, what they do is envelop grease and dirt particles in what are called micelles, making it possible for them to float in water.” One side of the surfactant is water-soluble, the other fat-soluble. The fat-soluble ends collect around non-polar, non-water soluble compounds such as grease or around particles, and “trap” them in a micelle. The water-soluble, polar ends of the surfactants, on the other hand, point towards the water molecules, allowing the microscopically small micelle to float in water.

A box of sugar cubes in the Walchensee lake

The researchers applied this principle to the nanoparticles. “When the micelles surrounding the particles are warmed slightly, they start to clump”, explains Schuster. This turns the water cloudy. Using a centrifuge, the surfactants and the nanoparticles trapped in them can then be separated from the water. This procedure is called cloud point extraction. The researchers then use the surfactants that have been separated out in this manner – which contain the particles in an unmodified, but highly concentrated form – to measure how many silver nanoparticles are present. To do this, they use a highly sensitive atomic spectrometer configured to only detect silver. In this manner, concentrations in a range of less than one nanogram per liter can be detected. To put this in perspective, this would be like detecting a box of sugar cubes that had dissolved in the Walchensee lake.

With the help of this analysis procedure, it is possible to gain new insight into the concentration of nanoparticles in drinking and waste water, sewage sludge, rivers, and lakes. In Bavaria, the measurements yielded good news: The concentrations measured in the water bodies were extremely low. In was only in four of the 13 Upper Bavarian lakes examined that the concentration even exceeded the minimum detection limit of 0.2 nanograms per liter. No measured value exceeded 1.3 nanograms per liter. So far, no permissible values have been established for silver nanoparticles.

Representative for watercourses, the Isar river was examined from its source to its mouth at around 30 locations. The concentration of silver nanoparticles was also measured in the inflow and outflow of sewage treatment plants. The findings showed that at least 94 percent of silver nanoparticles are filtered out by the sewage treatment plants.

I was saddened and discouraged to read that the ‘top kill’ solution for the BP oil spill in the Gulf of Mexico didn’t work. I can only imagine how people who are directly affected feel. As this crisis continues, I begin to better appreciate how interconnected we are on this planet.

Specifically, I’ve come across a local (Vancouver, Canada) debate about oil spills and liability. One of the daily newspapers and a news station recently featured information about a local marine oil spill (from a Chevron refinery) which occasioned debate on a Vancouver civic blog about environmentalists, hyprocrisy, the desire for oil, and reflections on crime, punishment, and what’s occurring in the Gulf of Mexico.

CityCaucus.com has a May 29, 2010 posting (Oil refinery irony) which makes some harsh points about environmentalists going to check the local oil spill via a motorboat. The points are true and the option suggested, canoeing to the site, is difficult for me to grasp as being a serious option which drove home for me not just the dependency on oil but also the unconscious reliance on how and the speed at which news is conveyed.

The piece managed to attract a very focused and succinct summary about BP’s culpability. First, the quote which mobilized the comment (from the May 29, 2010 posting),

As Vancouver technologist and Twitter fiend Tim Bray said yesterday:

Unlike apparently everyone, I’m not pissed at BP. You gonna live on fossil fuel, shit gonna happen. BP drew the short straw.

It’s certainly concise (how could it be otherwise with a 140 character limit?) and, I think, true in its way. We do live on fossil fuel and as the sources diminish we will be extracting that fuel in more complex and dangerous ways. Still, Sean Bickerton pointed out in his comment (May 29, 2010 posting on the CityCaucus blog) a few issues with BP,

While our need for oil drives exploration in more and more technologically challenging environments, it’s not demand that produced the worst environmental disaster in American history – that would be the negligence, fraud, incompetence, and greed of a reckless BP that:

* bypassed even minimal safety precautions

* used the cheapest casing and sealants known to have exploded on other rigs

* ignored clear safety concerns of their own crews and engineers

* ignored the fact their own well was out of control, insisting underlings cover up the explosive gas coming up the pipe

* refused to undertake adequate testing of the blowout valve despite known problems

* had no backup plan or equipment in place despite mounting dangers on the rig.

We have every right to insist that risky exploration and drilling be done to the highest environmental and safety standards, and that companies put their worker’s safety and the environment before gouging another penny of profit out of the most lucrative business in the world.

Whether a sin of commission or omission, If terrorists had done what BP has done, killing eleven workers on that rig and fouling the entire Gulf Coast and much of the Gulf of Mexico, the full might of the international community would have been mobilized to attack the entity responsible and all of their assets would have been seized.

Where crimes have been committed, those responsible should be prosecuted to the fullest extent of the law.

I can’t speak to the accuracy of the list other than to observe that with a catastrophe of this size, more than one thing went wrong and this list covers major points.

Meanwhile, the debate over the attempts to mitigate the damage have fostered a controversy over a solution that claimed to be nanotechnology-enabled. Andrew Shneider at AOL News has written a piece, which has some good points and some misinformation all pulled together into a toxic brew.

The company, Green Earth Technologies, has applied to use what they claim is a nano-enabled dispersant for the oil spill in the Gulf. There has been strong opposition to this as noted in Schneider’s article. At this point, Schneider finds an expert who makes comments that suggest he is not familiar with any of the nanotechnology research he appears to be referring to.

Andrew Maynard at 2020 Science provides an analysis of the company’s (Green Earth Technologies) product and notes that the company did not do itself any favours by being overoptimistic in its product safety claims. Andrew excerpts the company’s website product description in his posting,

G-MARINE Fuel Spill Clean-UP! is a unique blend of plant derived, water based and ultimate biodegradable ingredients specifically formulated to quickly emulsify and encapsulate fuel and oil spills. These plant derived ingredients are processed to form a colloidal micelle whose small particle size (1-4 nanometers) enables it to penetrate and breakdown long chain hydrocarbons bonds in oils and grease and holds them in a colloidal suspension when mixed with water. Once oil has been suspended in a nano-colloidal suspension, there is no reverse emulsion; the oil becomes water soluble allowing it to be consumed by resident bacteria in the water. This dispersant formula is protected by trade secrets pursuant to Occupational Safety and Health Agency (OSHA) Standard CFR-1910 1200. The ingredient list has been reviewed by the US EPA and contains no ingredients considered hazardous by OSHA.

Here’s where the company went overboard,

Does G-MARINE OSC-1809 Oil & Fuel Spill Clean-UP! have any adverse affects on humans / animals or the environment?

Do read Andrew’s textual analysis of how the NGO’s got it confused, a description of how the term nanoparticle is being used as a synonym for carbon nanotube and, for fun, read the comments. Schneider’s expert showed up to question Andrew’s credibility as an expert.

I also found this post by Tim Harper, principal of Cientifica and author of the TNT Log. From a May 29, 2010 post he made prior to attending the latest World Economic Forum meeting,

I often despair when policy on environment and health issues seems to be made without any recourse to science, whether on MMR vaccines, GMO’s or the Louisiana clean up.

…

The real question I’ll be looking at in Doha [where the World Economic Forum is being held] is [how] much longer are we going to have to wade through obfuscation from all sides while the planet dies?

I quite agree with the sentiment. We don’t have time and I am tired of obfuscation from all sides.

Pour revenir à mes moutons (meaning: getting back to where I started, the literal meaning: returning to my sheep), I think the impact of this oil spill will be felt in ways that we cannot yet imagine and those ways will be profound and global.